1. Field of the Invention
The present invention relates to a photographic developing agent and more particularly to a photographic developing agent capable of releasing a development inhibitor at the step of development; a silver halide photographic light-sensitive material which has a photographic layer containing the same; and a process for developing images by treating a photographic light-sensitive material with a developer containing the same.
2. Description of the Prior Art
Hitherto, hydroquinone derivatives releasing a development inhibitor depending upon the density of image at the time of development (so-called DIR hydroquinones) are known. Typical examples of known DIR hydroquinones are described in U.S. Pat. Nos. 3,379,529 and 3,620,746, and Japanese Patent Application (OPI) No. 129,536/1974, etc. These DIR hydroquinones are, as described in the above patents, used for the purpose of attaining the so-called DIR effect, e.g., control of image tone, an improvement in graininess, image sharpness and color reproduction, etc.
Although these DIR hydroquinones have desirable properties, they also have various defects. One defect is that a sufficient DIR effect cannot be obtained because of insufficient activity of the compounds. A second defect is that incorporation of the compound into a light-sensitive emulsion layer as a dispersion deteriorates the storage stability of the light-sensitive material. A third defect is that synthesis of the compounds is not easy. A fourth defect is that a reduction in storage stability with time of a coating solution containing the compound deteriorates the photographic properties.